The steadily increasing domestic and industrial energy demand can only be satisfied by optimal utilization of all available resources. The aim of this project is the design and construction of an improved small-scale combustion unit for biofuels like wood, straw pellets, and especially grain. Using computational fluid dynamics (CFD) methods and measurement data from a pilot unit, this study contributes to the continuous enhancement of the biomass firing technology by addressing the commonly known problems regarding emissions and ash melting. Based on the calculated results improvements for the existing prototype, new geometry has been suggested and was planned to be included in the design of a new 1.5-MW pilot-scale grate firing unit that was to start operation in early 2009.